A warm-up catalytic converter (WCC)of a vehicle purifies exhaust gas emitted from a vehicle engine has an inlet portion welded to a turbine housing.
As illustrated in FIGS. 1 and 3, a flange 101 of a turbine housing is welded to inlet portions of front cones 102 and 102′ of a WCC, such that exhaust gas emitted from a turbine of the turbocharger enters the WCC.
A method for welding the front cones 102 and 102′ to the flange 101 can be divided into an inner peripheral welding method as illustrated in FIGS. 1 and 2 and an outer peripheral welding method as illustrated in FIGS. 3 and 4.
The inner peripheral welding method fixes the front cone 102 to the flange 101 by inserting the inlet portion of the front cone 102 into a through hole formed in the flange 101 and then welding the front cone 102 to the flange 101 within the through hole. The inner peripheral welding method is made when an interval G1 between the flange 101 and an outer peripheral surface of the front cone 102 is narrow, and thus, a welding tool may not enter into the interval therebetween. As a result, the exhaust system can be minimized A catalyst may be activated in the early stage by improving dynamic stiffness, improvement in noise, vibration, and harshness (NVH), and shortening an exhaust passage due to the small size of the exhaust system. However, as a welded portion 103 is directly exposed to a high-temperature exhaust gas, contraction and expansion stress may apply to the flange 101, thus decreasing durability against thermal fatigue.
In the outer peripheral welding method, the inlet portion of the front cone 102′ is inserted into the through hole of the flange 101 and then welding is applied at which an outer peripheral surface of the front cone 102′ meets the flange 101. The outer peripheral welding method can reduce an exposure temperature and disperse the contraction and expansion stress due to the welded portion 103 formed at outside the exhaust passage, but may reduce a catalyst capacity and may deteriorate the dynamic stiffness and the NVH due to an increase in sizes of the exhaust passage and the front cone 102′.